HAGATNA, Jan 22, 2010 (AFP) - Residents of the US territory of Guam fear the planned influx of thousands of American troops and their families will leave their Pacific island home swamped.

Around 19,000 personnel and their families are set to relocate to Guam from southern Japan in a move that will treble the US military presence on the island.

But despite proclaimed economic benefits, not all of the 178,000-strong population is looking forward to the troops' arrival.

"This proposed military build-up, with our current political status, will result in the cultural and racial genocide of the Chamorro people," said Frank J. Schacher, chairman of the Chamorro Tribe Inc., a group representing the island's indigenous people, who make up a third of the population.

"It is our island, our ancestral remains, our sacred artifacts, our waters, our culture, and our right to exist as a race that would be destroyed by these intended actions."

It is a long time since the Chamorro have been masters of their own destiny: Spain controlled the island for more than two hundred years until the late 19th century, when it was taken over by the United States, and it was occupied by Japan during World War II.

In 2006, Washington and Tokyo agreed to shift thousands of marines from Okinawa after complaints that, with half of the country's 47,000 US military personnel, the island was over burdened.

Guam's US Congress delegate, Madeleine Bordallo, hailed the plan as a great opportunity for the territory. The local government and the business community have also welcomed an expected economic boom fuelled by the build-up.

"Our future, however, will test our resolve and we will be called upon to display our commitment to doing what is good and right for our people."

An 11,000-page US Defense Department draft environmental impact statement said the military expansion would strain the island's limited infrastructure, healthcare, and ecology.

The study says the relocation, costing up to 15 billion dollars, would bring 8,600 marines, 630 army personnel, and about 10,000 dependents to Guam.

More than 33,000 foreign workers would also be needed to build wharves, aircraft carrier berths, roads, military barracks, and homes.

The Guam Chamber of Commerce, an early supporter of the relocation, said it was not oblivious to growing scepticism within the community.

"We're the voice of the businesses, but our members all live in Guam too. So we're looking out for the best interests of our businesses and the community at large and so we're looking at everything," Chamber president David Leddy said.

"There are positive and negative impacts. We just have to weigh the positive and negative and see what's good for the people."

About a third of Guam's 549 square kilometres (212 square miles) is already owned by the US government, mainly for military use, and it wants to buy another 2,200 acres (890 hectares) as part of the troop transfer.

"Lands that our ancestors fought for are passed down from one generation to the next until they are indiscriminately taken away for purposes other than sustaining and nourishing the family clan," said Gloria B. Nelson, whose property is being eyed by the Department of Defense.

Melvin Won Pat, one of the founders of a new activist group opposed to the build-up, said it was false to suggest the move was supported by the wider community.

"I think a lot of our people have been misled into believing the general population is in full support of this move," he said.

The Department of Defense's Joint Guam Project Office, which is in charge of the relocation, has held a series of public meetings to discuss the draft report, but some locals remain sceptical.